scholarly journals The first 5 years of gravitational-wave astrophysics

Science ◽  
2021 ◽  
Vol 372 (6546) ◽  
pp. eabc7397
Author(s):  
Salvatore Vitale
Keyword(s):  
General Relativity ◽  
Gravitational Wave ◽  
Electromagnetic Waves ◽  
Gamma Ray ◽  
Direct Consequence ◽  
Compact Objects ◽  
Tests Of General Relativity ◽  
Astrophysical Objects ◽  
Progenitor Stars ◽  
The Universe

Gravitational waves are ripples in spacetime generated by the acceleration of astrophysical objects; a direct consequence of general relativity, they were first directly observed in 2015. Here, I review the first 5 years of gravitational-wave detections. More than 50 gravitational-wave events have been found, emitted by pairs of merging compact objects such as neutron stars and black holes. These signals yield insights into the formation of compact objects and their progenitor stars, enable stringent tests of general relativity, and constrain the behavior of matter at densities higher than that of an atomic nucleus. Mergers that emit both gravitational and electromagnetic waves probe the formation of short gamma-ray bursts and the nucleosynthesis of heavy elements, and they measure the local expansion rate of the Universe.

scholarly journals The confrontation between general relativity and experiment

2009 ◽  
Vol 5 (S261) ◽  
pp. 198-199
Author(s):  
Clifford M. Will
Keyword(s):  
General Relativity ◽  
Gravitational Wave ◽  
Equivalence Principle ◽  
Gamma Ray ◽  
Strong Field ◽  
Weak Field ◽  
X Ray ◽  
Spacetime Geometry ◽  
Tests Of General Relativity ◽  
Laser Interferometric

AbstractWe review the experimental evidence for Einstein's general relativity. A variety of high precision null experiments confirm the Einstein Equivalence Principle, which underlies the concept that gravitation is synonymous with spacetime geometry, and must be described by a metric theory. Solar system experiments that test the weak-field, post-Newtonian limit of metric theories strongly favor general relativity. Binary pulsars test gravitational-wave damping and aspects of strong-field general relativity. During the coming decades, tests of general relativity in new regimes may be possible. Laser interferometric gravitational-wave observatories on Earth and in space may provide new tests via precise measurements of the properties of gravitational waves. Future efforts using X-ray, infrared, gamma-ray and gravitational-wave astronomy may one day test general relativity in the strong-field regime near black holes and neutron stars.

scholarly journals Recent LIGO-Virgo discoveries

2021 ◽  
pp. 2130010
Author(s):  
Maximiliano Isi
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Neutron Star ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Compact Objects ◽  
Tests Of General Relativity ◽  
Mass Gap ◽  
Cosmic History

The LIGO and Virgo gravitational-wave detectors carried out the first half of their third observing run from April through October 2019. During this period, they detected 39 new signals from the coalescence of black holes or neutron stars, more than quadrupling the total number of detected events. These detections included some unprecedented sources, like a pair of black holes with unequal masses (GW190412), a massive pair of neutron stars (GW190425), a black hole potentially in the supernova pair-instability mass gap (GW190521), and either the lightest black hole or the heaviest neutron star known to date (GW190814). Collectively, the full set of signals provided astrophysically valuable information about the distributions of compact objects and their evolution throughout cosmic history. It also enabled more constraining and diverse tests of general relativity, including new probes of the fundamental nature of black holes. This review summarizes the highlights of these results and their implications.

scholarly journals ON POSSIBLE GEOMETRIC AND ASTROPHYSICAL EFFECTS OF NONLINEAR SPINOR FIELDS IN THE MEGAMIR, MACROWORLD AND MICROWORLD

Metaphysics ◽  
2020 ◽  
pp. 82-93
Author(s):  
V. G Krechet
Keyword(s):  
General Relativity ◽  
Gravitational Interaction ◽  
Space Time ◽  
Elementary Particles ◽  
Nonlinear Spinor ◽  
Evolution Of The Universe ◽  
Spinor Fields ◽  
Astrophysical Objects ◽  
Local Space ◽  
The Universe

In this article, within the framework of general relativity, the possible effect of the gravitational interaction of Dirac nonlinear spinor fields on the evolution of the Universe, on the formation of astrophysical objects and on the formation of the geometry of the local space-time of elementary particles with spin ħ / 2 is considered.

scholarly journals High-energy astrophysics and the search for sources of gravitational waves

2018 ◽  
Vol 376 (2120) ◽  
pp. 20170294 ◽  
Author(s):  
P. T. O'Brien ◽  
P. Evans
Keyword(s):  
Gravitational Wave ◽  
Short Duration ◽  
Gamma Ray ◽  
New Technology ◽  
High Energy ◽  
Compact Objects ◽  
Wide Field ◽  
High Energy Radiation ◽  
Energy Radiation ◽  
Binary Mergers

The dawn of the gravitational-wave (GW) era has sparked a greatly renewed interest into possible links between sources of high-energy radiation and GWs. The most luminous high-energy sources—gamma-ray bursts (GRBs)—have long been considered as very likely sources of GWs, particularly from short-duration GRBs, which are thought to originate from the merger of two compact objects such as binary neutron stars and a neutron star–black hole binary. In this paper, we discuss: (i) the high-energy emission from short-duration GRBs; (ii) what other sources of high-energy radiation may be observed from binary mergers; and (iii) how searches for high-energy electromagnetic counterparts to GW events are performed with current space facilities. While current high-energy facilities, such as Swift and Fermi, play a crucial role in the search for electromagnetic counterparts, new space missions will greatly enhance our capabilities for joint observations. We discuss why such facilities, which incorporate new technology that enables very wide-field X-ray imaging, are required if we are to truly exploit the multi-messenger era. This article is part of a discussion meeting issue ‘The promises of gravitational-wave astronomy’.

The stellar graveyard

2019 ◽  
pp. 177-206
Author(s):  
Nils Andersson
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Stellar Evolution ◽  
White Dwarfs ◽  
Supermassive Black Holes ◽  
Compact Objects ◽  
Fermi Gases ◽  
The 1950S

This chapter introduces the different classes of compact objects—white dwarfs, neutron stars, and black holes—that are relevant for gravitational-wave astronomy. The ideas are placed in the context of developing an understanding of the likely endpoint(s) of stellar evolution. Key ideas like Fermi gases and the Chandrasekhar mass are discussed, as is the emergence of general relativity as a cornerstone of astrophysics in the 1950s. Issues associated with different formation channels for, in particular, black holes are considered. The chapter ends with a discussion of the supermassive black holes that are found at the centre of galaxies.

scholarly journals Asymptotically flat vacuum solution in modified theory of Einstein’s gravity

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Surajit Kalita ◽  
Banibrata Mukhopadhyay
Keyword(s):  
General Relativity ◽  
Vacuum Solution ◽  
Compact Objects ◽  
Schwarzschild Solution ◽  
Asymptotically Flat ◽  
Symmetric Vacuum ◽  
Theory Of Gravity ◽  
Bound Orbits ◽  
Vacuum Spacetime ◽  
The Universe

Abstract A number of recent observations have suggested that the Einstein’s theory of general relativity may not be the ultimate theory of gravity. The f(R) gravity model with R being the scalar curvature turns out to be one of the best bet to surpass the general relativity which explains a number of phenomena where Einstein’s theory of gravity fails. In the f(R) gravity, behaviour of the spacetime is modified as compared to that of given by the Einstein’s theory of general relativity. This theory has already been explored for understanding various compact objects such as neutron stars, white dwarfs etc. and also describing evolution of the universe. Although researchers have already found the vacuum spacetime solutions for the f(R) gravity, yet there is a caveat that the metric does have some diverging terms and hence these solutions are not asymptotically flat. We show that it is possible to have asymptotically flat spherically symmetric vacuum solution for the f(R) gravity, which is different from the Schwarzschild solution. We use this solution for explaining various bound orbits around the black hole and eventually, as an immediate application, in the spherical accretion flow around it.

scholarly journals Multiparameter Tests of General Relativity Using Multiband Gravitational-Wave Observations

2020 ◽  
Vol 125 (20) ◽  
Author(s):  
Anuradha Gupta ◽  
Sayantani Datta ◽  
Shilpa Kastha ◽  
Ssohrab Borhanian ◽  
K. G. Arun ◽  
...  
Keyword(s):  
General Relativity ◽  
Gravitational Wave ◽  
Tests Of General Relativity

Future prospects for y-ray astronomy

1981 ◽  
Vol 301 (1462) ◽  
pp. 693-701 ◽  
Keyword(s):  
Gamma Ray ◽  
Dynamic Pressure ◽  
High Energy ◽  
Compact Objects ◽  
Pressure Effects ◽  
Very High Energy ◽  
Order Of Magnitude ◽  
High Energy Particles ◽  
Nuclear Processes ◽  
The Universe

As y-ray astronomy moves from the discovery to the exploratory phase, the promise of y-ray astrophysics noted by theorists in the late 1940s and 1950s is beginning to be realized. In the future, satellites should carry instruments that will have over an order of magnitude greater sensitivity than those flown thus far, and, for at least some portions of the y-ray energy range, these detectors will also have substantially improved energy and angular resolution. The information to be obtained from these experiments should greatly enhance our knowledge of several astrophysical phenomena including the very energetic and nuclear processes associated with compact objects, astrophysical nucleosynthesis, solar particle acceleration, the chemical composition of the planets and other bodies of the Solar System, the structure of our Galaxy, the origin and dynamic pressure effects of the cosmic rays, high energy particles and energetic processes in other galaxies especially active ones, and the degree of matter-antimatter symmetry of the Universe. The y-ray results of the forthcoming programs such as Gamma-I, the Gamma Ray Observatory, the y-ray burst network, Solar Polar, and very high energy y-ray telescopes on the ground will almost certainly provide justification for more sophisticated telescopes. These advanced instruments might be placed on the Space Platform currently under study by N.A.S.A.

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